Surgical instrument

ABSTRACT

A construction of surgical scissors with replaceable blades wherein the pivotal connection between the scissor shanks includes a first fastener threadingly binding together the shanks, a second fastener cooperating with the first fastener causing an expansion of the first fastener into tighter cooperation with the shanks. A nonmetallic, hard surface, low friction, bearing surface element is located between the shanks adjacent the pivotal connection. A first embodiment of replaceable blade structure wherein a longitudinal dovetail projection is formed upon the blade which is to cooperate with a dovetail recess located within the cutting edge portion of the shank. A slit is provided within the shank to effect resilient movement of the shank about the dovetail. A set screw is provided within the shank to clamp together the shank about the dovetail when the blade is positioned as desired. In a second embodiment of the replaceable blade structure, the blade has a longitudinal access slot within the body portion of the blade. A recess is located upon the lower edge of the slot approximately at the midpoint of the slot length. The recess is to cooperate with a pin fixedly located within the shank of the scissors. In a third embodiment of the replaceable blade structure, a screw, located within the shank, within an eccentric section is to be rotatable into frictional abutting contact with the blade to retain the blade in position with the shank. In a fourth embodiment of the replaceable blade structure, a shoulder upon the set screw which is located within the shank is to cooperate with a recess located within the body portion of the blade.

United States Patent Rose [ June 20, 1972 [54] SURGICAL INSTRUIVIENT Anthony T. Rose, 603 Hudspeth Ave., Simi, Calif. 93065 [22] Filed: June 12, 1970 [21] Appl.No.: 45,803

[72] Inventor:

Primary Examiner-Theron E. Condon Assistant Examiner-J. C. Peters Attorney-Robert E. Geauque [5 7] ABSTRACT A construction of surgical scissors with replaceable blades wherein the pivotal connection between the scissor shanks includes a first fastener threadingly binding together the shanks, a second fastener cooperating with the first fastener causing an expansion of the first fastener into tighter cooperation with the shanks. A nonmetallic, hard surface, low friction, bearing surface element is located between the shanks adjacent the pivotal connection. A first embodiment of replaceable blade structure wherein a longitudinal dovetail projection is formed upon the blade which is to cooperate with a dovetail recess located within the cutting edge portion of the shank. A slit is provided within the shank to effect resilient movement of the shank about the dovetail. A set screw is provided within the shank to clamp together the shank about the dovetail when the blade is positioned as desired. in a second embodiment of the replaceable blade structure, the blade has a longitudinal access slot within the body portion of the blade. A recess is located upon the lower edge of the slot approximately at the mid-point of the slot length. The recess is to cooperate with a pin fixedly located within the shank of the scissors. In a third embodiment of the replaceable blade structure, a screw, located within the shank, within an eccentric section is to be rotatable into frictional abutting contact with the blade to retain the blade in position with the shank. In a fourth embodiment of the replaceable blade structure, a shoulder upon the set screw which is located within the shank is to cooperate with a recess located within the body portion of the blade.

3 Claims, 16 Drawing [figures SURGICAL INSTRUMENT BACKGROUND OF THE INVENTION A scissors is an extremely old instrument which usually comprises a pair of pivotally connected shanks in which one end of each of the shanks includes means to facilitate manual movement thereof with the other end of each of the shanks including a cutting edge. The cutting action of the scissors is achieved by moving the shanks so that cutting blade of each of the shanks comes together in an abutting relationship with the object to be cut located therebetween.

It has been most common in scissor instruments (any instrument having pivotally connecting arm elements) to bind the shank elements of the scissor together as by means of a common fastening means such as a screw or a bolt and nut combination. There are many disadvantages to such a type of pivotal connection. One disadvantage is that the fastener which is employed usually has a relatively small diameter head surface. As a result, non-planar movement is permitted between the shank elements. Although this play" is not significant, such is undesirable as it tends to decrease cutting efficiency. Frequently, the fastener that forms the pivotal connection has been installed initially in a permanent manner and cannot be tightened to decrease such play." Another disadvantage is that as the scissors are used over a period of time, galling occurs of the fastener and between the shank elements. This galling also causes play until finally a complete loss of the cutting action is achieved. At that point, the complete scissor element must be discarded. The third disadvantage to such type of scissors is that, over a period of time, as the cutting edge becomes dull the sharpening thereof also increases play." Such sharpening shortens the life of the scissors.

In the surgical area of medicine, the use of scissors is extremely important Such scissors are employed to cut difficult type materials as gauze bandages, human skin and the like. Therefore, it is desirable for such scissors to be absolutely as sharp as possible and to remain so during the entire lift of the scissors. Also, it is desired that these scissors shall not require sharpening.

Heretofore, in an effort to achieve scissors desirable for use in medicine, such scissors have been formed of an extremely hard material such as stainless steel or the like. In order for the scissor elements to maintain an extremely sharp edge during use over a period of years, the scissors have been coated with a harder material as by chrome plating. Also, in the past such scissors have been made with substantially high precision with the cutting edge being extremely finely ground. As a result of the previous employed hard materials and fabrication techniques, such a scissors therefore has become quite costly. Although such a scissors will last, with normal use, 3 to 5 years, it is desirable for a scissors to last a greater length of time as ten or more years. it has been found that the basic material of construction of the scissors does not result in the discarding of the scissors. The discarding results from failure of the pivotal connection between the shanks or loss of the cutting ability of the scissors.

SUMMARY OF THE INVENTION The scissor construction of this invention employs the use of first and second shank elements which are to be pivotally connected together by first and second fasteners. The first fastener has a substantially greater diameter head portion than fasteners used previously with the head portion cooperating with a recess located within the first shank element. The first fastener extends through an aperture in the first shank element and cooperates in a screw threading manner with the second shank element. A nonmetallic washer element is to be located between the shank elements about the first fastener to eliminate galling therebetween. A desirable form of washer material would be polytetrafluorethylene resin or other synthetic resins or plating. A second fastener cooperates within a recess of the second shank element with the second fastener cooperating with the first fastener in a screw threading manner. A longitudinal slot is formed within each side of the first fastener which causes the first fastener to increase in diameter upon being wedged by the second fastener.

To facilitate replacement and retention of the blade in cooperation with the shank element of the scissors, the first embodiment of the replaceable blade structure provides for the integral attachment of a longitudinal dovetail to each blade. The dovetail is to matingly cooperate with a dovetail recess formed in the top of each shank element adjacent the cutting edge area. A slit is to be formed longitudinally along each shank and extend from the dovetail recess approximately two-thirds of the shank depth. A set screw is to be provided perpendicular to the slit and communicating with the slit. The set screw is to cause fixing of the blade with respect to the shank by clamping the separate shank elements due to the slit against the dovetail of the blade. The set screw can take the form of a normal screw fastener or a screw fastener arrangement similar to the pivotal connection of the shank elements as previously described.

In the second embodiment of the replaceable blade structure of this invention, the dovetail has been replaced by a longitudinal, substantially rectilinear body element. Within the body element, a longitudinal slot is provided with a recess being located within the lower edge of the slot. Within the shank a pin is fixedly secured extending through the longitudinal slit within the shank. Each blade is to cooperate with its respective shank so that the longitudinal slot, particularly the recess therein, cooperates with the fixed pin within the shank.

The third embodiment of the replaceable blade structure of this invention provides for the employment of a dovetailed blade arrangement similar to the arrangement as defined in the first embodiment. However, instead of a slit being employed within each shank and an appropriate set screw arrangement, an eccentric set screw is employed within the shank which, when rotated, is capable of moving an eccentric cam surface (a portion of the set screw) into frictional abutting arrangement with the dovetail projection of the blade.

In the fourth embodiment of the replaceable blade structure of this invention, a blade structure similar to that of the second embodiment is employed in that a substantially rectilinear body portion is provided. However, instead of a longitudinal slot, a vertical slot is provided within the body portion which communicates with a disc shaped recess also located within the body portion. The body portion of the blade is then to be located in an appropriate longitudinal slit within each shank so that the vertical slot cooperates with a set screw located within the shank and communicating with the slit. Upon the body portion of the blade being completely inserted within the shank, rotation of the set screw will cause cooperation of a shoulder portion of the set screw with the disc shaped recess.

It is an object of the apparatus of this invention to provide a scissors construction which is substantially long wearing and will last many years under normal use.

It is another object of the apparatus of this invention to pr0- vide a pivotal connection for scissor shanks wherein the wear caused by such connection is substantially decreased.

It is another object of the apparatus of this invention to provide a scissors wherein the cutting blades may be replaced upon becoming dull.

Another object of the apparatus of this invention is to employ a pivotal connection between the shank elements of a pair of scissors wherein adjustment is permitted to compensate for wear due to prolonged use of the scissors.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of the replaceable blade scissors of this invention embodying the pivotal connection between the shanks of this invention;

FIG. 2 is an enlarged, fragmentary view of the pivotal connection of this invention taken along lines 2-2 of FIG. 1; FIG.

3 is a sectional view through the pivotal connection of this invention taken along lines 3-3 of FIG. 2;

FIG. 4 is a view similar to FIG. 1 but showing the scissors in the open position;

FIG. 5 is a partially cut out perspective view through one of the shanks of the scissors showing in more detail a first embodiment of the replaceable blade structure of this invention;

FIG. 6 is a sectional view through one of the scissor shanks taken along lines 66 of FIG. 4;

FIG. 7 is a view similar to FIG. 6 but showing a modification of the shank construction;

FIG. 8 is a longitudinal, partially cut out, side view of a scissor shank showing a second embodiment of the replaceable blade structure of this invention;

FIG. 9 is a sectional view of the second embodiment of the replaceable blade structure of this invention taken along line 99 of FIG. 8;

FIG. 10 is a partially cut out, perspective view of a scissor shank showing in more detail a third embodiment of the replaceable blade structure of this invention;

FIG. 11 is a longitudinal, partly-in-section view of the set screw employed in FIG. 10 wherein the set screw is in a nonengaging position with the blade to permit movement of the blade with respect to the shank;

FIG. 12 is a view similar to FIG. 11 but showing the set screw in the engaging position with the blade;

FIG. 13 is a cross-sectional view through a scissor shank employing a fourth embodiment of the replaceable blade structure of this invention;

FIG. 14 is a portion of the replaceable blade structure of the fourth embodiment of this invention in a perspective view;

FIG. 15 is a view similar to FIG. 13 but showing the blade in the non-engaging position with the scissor shank; and

FIG. 16 is a longitudinal exploded view of the fastener employed in the fourth embodiment of the invention.

DETAILED DESCRIPTION OF THE SHOWN EMBODIMENT Referring particularly to the drawings, there is shown in FIG. 1 a scissors 10 being formed of a first shank 12 and a second shank 14. The aft ends of the shanks 12 and 14 are formed into openings 16 and 18, respectively, to facilitate cooperation with the fingers of a person. The forward end of each of the shanks l2 and 14 is formed into blades 20 and 22, respectively. Blades 20 and 22 are to be movable together in an abutting relationship by means of movement of the shanks 12 and 14 about pivotal connection 24.

Pivotal connection 24 includes the use of a first fastener 26 and a second fastener 28. Both the first fastener 26 and the second fastener 28 include recesses 30 within their respective heads 32 and 34. The recesses function to facilitate engagement by a tool (not shown) to effect rotation of the fasteners 26 and 28. Head 32 is of a substantially greater diameter than normal fasteners which are commonly employed in such connections. Head 34 is also of a greater diameter than conventional fasteners; however, it is shown to be not as large as head 32. The reason for the increased size of heads 32 and 34 is that such an arrangement tends to prevent movement of the shanks in any direction other than the desired pivotal movement. The head 32 of the fastener 26 matingly cooperates within a recess 36 formed within the first shank 12. Head 34 is adapted to cooperate within recess 38 formed within second shank 14. The connecting portion 40 of the fastener 26 extends centrally from head 32 through an aperture 42 within the first shank 12 and into a second aperture 44 located within second shank 14. The outermost portion of connecting portion 40 is screw threaded and is to cooperate in a screw threading manner with aperture 44. Connecting portion 40 includes a longitudinal slot 46, the function of which will be explained further along in the description.

Centrally connected to head 34 of fastener 28 is a wedgeshaped portion 48. The connecting portion 50 extends from the wedge-shaped portion 48 with screw threads formed thereon which are to cooperate with internal screw threads located within connecting portion 40. A washer 52 is to surround connecting portion 40 and is to be located between shanks l2 and 14. Washer 52 is to cooperate with a recess 54 of the first shank 12 and a recess 56 of the second shank 14. The size of the washer 52 is to be selected to be of a thickness slightly greater than the combined depths of recesses 54 and 56. Therefore, with the washer so located and the pivotal connection 24 established, the surfaces of the shanks 12 and 14 are not in a contactual relationship. The material of construction of washer 52 is desired to facilitate low frictional movement. An example of a desired form of material of construction of washer 52 would be a polytetrafluorethylene resin, commonly known as Teflon." It is to be understood that any material which exhibits low frictional qualities would be desirable, many such synthetic resins or plastics being available.

To illustrate the first embodiment of the replaceable blade structure of this invention, within the shank 12 adjacent the cutting edge portion is formed a longitudinal dovetail slot 58. A dovetail projection 60 is connected to blade 20 and is to cooperate with the slot 58. Blade 20 is thereby removable and replaceable into cooperation with shank 12. It is to be understood that blade 22 includes a similar dovetail projection (not shown) which is to cooperate in a similar manner with a dovetail slot (not shown) within the second shank 14. A slit 62 is formed within the first shank 12 which extends substantially the entire length of the blade 20. A threaded opening 64 is located within the first shank 12 and passes through the slit 62. Within the threaded opening 64 a set screw 66 is to be located. Upon tightening of set screw 66, the elements of shank 14 separated by slit 62 are forced together with a clamping action being achieved against the dovetail projection 60. It is to be understood that shank 14 also includes a similar slit and set screw arrangement (not shown).

Referring particularly to FIG. 7 of the drawings, the shank 12 is shown as previously with a slit 62. However, the blade 20 is attached to a rod-like projection 68 which is to cooperate with a similar cylindrical opening 71 within the shank 12 in a manner similar to cooperation between the dovetail projection 60 and the dovetail slot 58. Also, if desired, the set screw 66 may be replaced by a first and second fastener arrangement 70 and 72, respectively, which would be similar to the pivotal connection 24.

In referring particularly to FIGS. 8 and 9 of the drawings, the second embodiment of the replaceable blade structure of this invention is shown. A shank 78 of a scissors has a longitudinal slit 80 formed therein similar to slit 62. However, slit 80 is of a greater width than slit 62. A pin 82 is located across slit 80 and is fixedly secured to the shank 78 at each end thereof. The location of pin 82 has been preselected and installed at a desired location. The blade 84 has a substantially rectilinear projection 86 extending longitudinally from the lower surface of blade 84. A slot 88 is formed longitudinally and substantially parallel to the upper surface of the blade 84 within the projection 86. Slot 88 is to be open to the side of the projection which is located nearest the pivotal connection of the scissor shanks. Because of the forming of slot 88, a resilient arm 90 is formed at the lowermost portion of projection 86. The inner surface of arm 90 includes a recess 92 at approximately the mid-point of the length of slot 88. The interior surface of arm 90 at its open end is inclined to achieve a cam surface 94.

To effect installation of blade 84 within shank 78, a person need only to insert the projection 86 within slit 80 until cam surface 94 comes into contact with pin 92. Further inward movement of blade 84 causes arm 90 to resiliently deflect a small amount until pin 92 rides upon the interior surface of arm 90. Upon completion of the insertion movement of blade 84, the location of recess 92 is such as to cooperate with pin 82. As a result, a locking action is achieved between the blade 84 and the shank 78 whereby the arm 90 is biased upwardly tending to maintain pin 82 into cooperation with recess 92.

To effect removal of blade 84, a sufficient longitudinal force must be applied against blade 84 until arm 90 is biased downwardly resulting in removal of pin 82 from recess 92. Further movement of blade 84 will result in removal of the blade 84 from cooperation with the slit 80.

Referring particularly to FIGS. through 12 of the drawings, a scissor shank 96 is attached to a blade 98 through cooperation with a dovetail projection 100 with a dovetail slot 102. It is to be understood that numerous other types of blade retention arrangements other than a dovetail type of arrangement could be employed, such as that shown in FIG. 7 of the drawings. A set screw 104 is located within shank 96 adjacent to dovetail slot 102. Set screw 104 includes an off-center mounted portion 106. Portion 106 could be basically any smooth surface configuration such as an elliptical shape or the like. The location of set screw 104 is to be such that upon rotation of set screw 104, portion 106 is capable of coming into contact with projection 100 when it is in a cooperative relationship with slot 102. By this arrangement, upon portion 106 coming into frictional contact with projection 100, secure retention of blade 98 in cooperation with shank 96 results.

The fourth embodiment of the replaceable blade structure of this invention is shown in FIGS. 13 through 16 of the drawings. Blade 108 is to cooperate with shank 110 by means of projection 112 within slit 114. Vertically disposed within projection 1 12 is a slot 1 16 which is opened at the lowermost edge of projection 112 and cooperates with a disc-shaped recess 1 18. A set screw 120 is to be secured within shank 110 with set screw 120 including a smaller diameter portion 122 and an enlarged shoulder 124. The selection of the size of portion 122 is to be such as to permit entry within slot 116. The size of the enlarged shoulder 124 is to matingly cooperate within recess 118. To install blade 108 in cooperation with shank 110, the set screw 120 is located so that shoulder 124 is not in communication with slit 114. The slot 116 is then permitted to pass over portion 122 of set screw 120 until full cooperation of blade 108 with shank 110 results. With the blade 108 in this position, upon tightening of set screw 120, the shoulder 124 will thereby matingly cooperate with recess 118 and provide a positive lock between the shank 110 and the blade 108 preventing its removal. To insure against undesired removal of set screw 120, a lock screw 121 is employed. Lock screw 121 is to be inserted within a corresponding aperture 123 within the shank 110. Lock screw 121 includes a left-handed thread portion 125 which is to internally cooperate with set screw 120. It is not necessary that portion 125 be left-handed but only threaded in the opposite direction to portion 122 of set screw 120. Upon set screw 120 being installed so shoulder 124 cooperates with recess 118, lock screw 121 is cooperatively located with set screw 120 as shown in FIG. 13 of the drawings. Thereupon, any attempt to remove set screw 120, without first removing lock screw 121, is prevented because lock screw 121 is just tightened upon shank 110 as is also set screw 120. This is due to the lefthanded thread arrangement between set screw 120 and lock screw 121. If it is desired to institute a loose connection, a small gap can be located between lock screw 121 and shank 110 as by backing off" lock screw 121 one hundred and eighty degrees.- During use of the scissors, the looseness of the connection can never exceed that established by the lock screw 121.

With the shanks 12 and 14 in the closed abutting relationship, a protuberance 74 which is attached to shank portion 14 cooperates within a recess 76 within shank portion 12. Fromberance 74 insures perfect cooperation between shanks 12 and 14 during movement to the closed position to effect the cutting action of the scissors 10. Also, when the scissors 10 are not being used, any exterior forces which are applied tending to tear apart shanks 12 and 14 are absorbed by the protubefastener 26 into cooperation with recess 36 of the shank 12.

The washer 52 is then placed about connecting portion 40 and into cooperative location within recess 54. y location of a tool (not shown) in cooperation with recesses 30, the first fastener 26 is then rotated so that the threaded section of connecting portion 40 is retained within aperture 44 of shank 14. The first fastener 26 is tightened sufficiently so as to firmly retain the first shank 12 to the second shank 14 with the minimum amount of "play" being permitted therebetween. Because of the enlarged size of heads 32 and 34, this play" is extremely minimal. However, although firm retention is required, because of the low frictional qualities of washer 52, ease of pivotal movement of one shank with respect to the other shank is permitted.

With the first fastener 26 so located in position, a second fastener 28 is located in a cooperative relationship with the first fastener 26. The second fastener 28 is tightened by a tool in cooperation with recesses 30 until the wedge-shaped portion 48 exerts a radially outward pressure against the threaded portion of connecting portion 40. Because of slot 46, slight deflection of connecting portion 40 is permitted, thereby increasing the tightness of the connection between shank element 14 and the connection element 40. As a result, a tight frictional bond occurs between connecting portion 40 and shank 14.

The blades 20, 22, 84, 98 and 108 may be made of any plastic or metallic material or any combination thereof. It may be desired, to form a long-lasting blade, to coat the blade with chrome or tungsten carbide. The cutting edges of the blades can be smooth or be serrated, whichever is desired for maximum cutting efficiency. To further increase the cutting efficiency, the upper surface of the blades may be formed convex or concave or slanted, whichever has been determined to be desirable. Also, the side of each blade adjacent the cutting edge may be beveled in a particular direction.

The term scissors" as used herein includes various types of devices in addition to scissors which utilize a scissor action, such as forceps, etc.

I claim:

1. A tool having a shank, a cutting blade being removably attached to said shank by a connecting means, said connecting means comprising:

a slit formed within said shank, a pin fixedly secured to said shank and traversing across said slit;

said cutting blade having a fore end and an aft end, a projection connected to the underside of said cutting blade and extending between said fore end and said aft end, said projection to matingly cooperate with said slit;

a longitudinal slot formed in said projection, said slot open at the edge of said projection adjacent said aft end, said slot forming a portion of said projection into an upper leg and a lower leg, said upper leg connected to said cutting blade;

a recess formed within said lower leg and communicating with said slot, whereby upon insertion of said projection within said slit said pin passes within said slot in contact with said second leg and causes a slight deflection of said second leg, said pin to cooperate with said recess upon complete insertion of said projection within said slit.

2. The tool of claim 1 wherein:

said recess located intermediate the ends of said longitudinal slot.

3. The tool of claim 1 wherein:

with said pin cooperating within said recess said fore end of said cutting blade being located in substantial alignment with the end of said shank. 

1. A tool having a shank, a cutting blade being removably attached to said shank by a connecting means, said connecting means comprising: a slit formed within said shank, a pin fixedly secured to said shank and traversing across said slit; said cutting blade having a fore end and an aft end, a projection connected to the underside of said cutting blade and extending between said fore end and said aft end, said projection to matingly cooperate with said slit; a longitudinal slot formed in said projection, said slot open at the edge of said projection adjacent said aft end, said slot forming a portion of said projection into an upper leg and a lower leg, said upper leg connected to said cutting blade; a recess formed within said lower leg and communicating with said slot, whereby upon insertion of said projection within said slit said pin passes within said slot in contact with said second leg and causes a slight deflection of said second leg, said pin to cooperate with said recess upon complete insertion of said projection within said slit.
 2. The tool of claim 1 wherein: said recess located intermediate the ends of said longitudinal slot.
 3. The tool of claim 1 wherein: with said pin cooperating within said recess said fore end of said cutting blade being located in substantial alignment with the end of said shank. 